/*
 * Copyright (c) 2015-2020, www.dibo.ltd (service@dibo.ltd).
 * <p>
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * <p>
 * https://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package com.icesoft.framework.core.binding.parser;

import com.icesoft.framework.core.util.S;
import com.icesoft.framework.core.util.V;
import lombok.extern.slf4j.Slf4j;
import net.sf.jsqlparser.expression.Expression;
import net.sf.jsqlparser.expression.operators.relational.EqualsTo;
import net.sf.jsqlparser.parser.CCJSqlParserUtil;
import net.sf.jsqlparser.schema.Column;

import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

/**
 * 条件管理器base类
 */
@Slf4j
public class BaseConditionManager {
	/**
	 * 表达式缓存Map
	 */
	private static final Map<String, List<Expression>> expressionParseResultMap = new ConcurrentHashMap<>();

	/**
	 * 获取解析后的Expression列表
	 *
	 * @param condition
	 * @return
	 */
	protected static List<Expression> getExpressionList(String condition) {
		if (V.isEmpty(condition)) {
			return null;
		}
		List<Expression> expressionList = expressionParseResultMap.get(condition);
		if (expressionList == null) {
			ConditionParser visitor = new ConditionParser();
			try {
				Expression expression = CCJSqlParserUtil.parseCondExpression(condition);
				expression.accept(visitor);
				expressionList = visitor.getExpressList();
				expressionParseResultMap.put(condition, expressionList);
			} catch (Exception e) {
				log.error("关联条件解析异常", e);
			}
		}
		return expressionList;
	}

	/**
	 * 提取中间表表对象名
	 *
	 * @param expressionList
	 * @return
	 */
	protected static String extractMiddleTableName(List<Expression> expressionList) {
		Set<String> tableNameSet = new HashSet<>();
		for (Expression operator : expressionList) {
			if (operator instanceof EqualsTo) {
				EqualsTo express = (EqualsTo) operator;
				// 均为列
				if (express.getLeftExpression() instanceof Column && express.getRightExpression() instanceof Column) {
					// 统计左侧列中出现的表名
					String leftColumn = express.getLeftExpression().toString();
					collectTableName(tableNameSet, leftColumn);
					// 统计右侧列中出现的表名
					String rightColumn = express.getRightExpression().toString();
					collectTableName(tableNameSet, rightColumn);
				}
			}
		}
		if (tableNameSet.isEmpty()) {
			return null;
		}
		if (tableNameSet.size() > 1) {
			log.warn("中间表关联条件暂只支持1张中间表！");
		}
		return tableNameSet.iterator().next();
	}

	/**
	 * 统计表名出现的次数
	 *
	 * @param tableNameSet
	 * @param columnStr
	 */
	private static void collectTableName(Set<String> tableNameSet, String columnStr) {
		if (!columnStr.contains(".")) {
			return;
		}
		// 如果是中间表(非this,self标识的当前表)
		if (!isCurrentObjColumn(columnStr)) {
			String tempTableName = S.substringBefore(columnStr, ".");
			tableNameSet.add(tempTableName);
		}
	}

	/**
	 * 是否为VO自身属性（以this开头的）
	 *
	 * @param expression
	 * @return
	 */
	protected static boolean isCurrentObjColumn(String expression) {
		String tempTableName = S.substringBefore(expression, ".");
		// 如果是中间表(非this,self标识的当前表)
		return "this".equals(tempTableName) || "self".equals(tempTableName);
	}
}
